1. Field of the Invention
The present invention relates to a manufacturing method of a semiconductor device, and particularly to a method for manufacturing a semiconductor device in which an element forming layer is peeled off a supporting substrate by using a peeling layer provided between the supporting substrate and the element forming layer.
2. Description of the Related Art
In recent years, the necessity of a card mounting an RFID (Radio Frequency Identification) or a tag mounting an RFID which can transmit and receive data without contact has been increased in any fields which need automatic recognition such as management of valuable securities and merchandise. The card mounting an RFID reads and writes data from/to an external device via a loop antenna in the card without contact. The card mounting an RFID has larger memory capacity and higher security than a magnetic card that records data by a magnetic recording method. Hence, a mode of the card mounting an RFID capable of being applied to various fields has been proposed recently.
In general, an RFID is constituted by an antenna and an IC chip which is formed by an element forming layer including a transistor and the like provided over a silicon wafer. In recent years, however, technological development of an RFID using an element forming layer provided over a glass substrate or the like has been advanced for cost reduction. According to such a technology, the element forming layer provided over the glass substrate is required to be separated from the glass substrate which is a supporting substrate after being completely manufactured. Various techniques have been contrived as a method for separating the element forming layer provided over the supporting substrate.
For example, there are a method of taking out an element forming layer by making a supporting substrate thin by grinding or polishing, a method of removing a supporting substrate by chemical reaction and the like, a method of peeling a supporting substrate and an element forming layer, and the like. As a method of peeling an element forming layer provided over a supporting substrate, there is a known technique that a separating layer formed of amorphous silicon (or polysilicon) is provided, and hydrogen contained in the amorphous silicon is released by laser light irradiation through a substrate, thereby a space is generated to separate the supporting substrate (see Patent Document 1). In addition, there is a technique that a peeling layer containing silicon is provided between an element forming layer and a supporting substrate, and the peeling layer is removed by using gas containing halogen fluoride to separate the element forming layer from the supporting substrate (see Patent Document 2). As described above, there are many methods for separating an element forming layer provided over a supporting substrate.
[Patent Document 1] Japanese Patent Laid-Open No. Hei 10-125929
[Patent Document 2] Japanese Patent Laid-Open No. Hei 8-254686
However, the methods of removing a supporting substrate by grinding, polishing, or dissolving cause problems such as a damage due to physical strength such as stress, and contamination. Furthermore, according to such methods, it is quite difficult to reuse a substrate and the cost is increased.
In the case where an element forming layer provided over a supporting substrate is separated by using a peeling layer provided between the supporting substrate and the element forming layer, the quality of the peeling layer becomes important. That is, in the case where a supporting substrate and an element forming layer are separated from each other by removing a peeling layer, time required for removing the peeling layer is affected depending on a material used for the peeling layer and an etchant used for removing the peeling layer. In addition, in the case where a supporting substrate and an element forming layer are separated from each other by physical strength via a peeling layer, the adhesiveness between the supporting substrate and the element forming layer which are formed with the peeling layer interposed therebetween is affected depending on a material used for the peeling layer. Furthermore, in the case where a element forming layer constituted by a thin film transistor and the like is provided on a peeling layer, the property of the transistor may be affected and the reliability of a semiconductor device may be decreased depending on a material or the film quality of the peeling layer.